Evan Thompson

June 17, 2024

​Surface chlorophyll data were collected on June 17, 2024 while the R/V Monitor was underway collecting bacteria samples in the Providence and Seekonk River estuaries. The average chlorophyll concentrations were categorized as poor in the Seekonk River and as fair in all other areas. Overall, chlorophyll ranged from 0.0 to 72.05 µg/L with an average of 13.74 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

May 29, 2024

​Phytoplankton samples were collected on May 29, 2024 at Bullock Reach and analyzed in the laboratory shortly after collection.

Sonde data revealed the surface water temperature was 20.1°C,  salinity was 15.49 psu, and chlorophyll a was 12.1 ug/L.

The qualitative tow net sample had a moderate filtration time, and the filtrate was a dark tan/brown color and had particulate matter.

The analysis of the quantitative whole water sample revealed a total of 7,565,000 cells per Liter. The most predominant phytoplankton genus was Skeletonema spp. at 7,276,000 cells/L. Other representative genera include Chaetoceros spp. and Leptocylindrus spp. Chaetoceros spp. (see 200x phase contrast image below) is a genus of diatoms found in Narragansett Bay and is one of the most common and most diverse genera of marine planktonic diatoms with over 200 accepted species. Due to its high growth rates, research has been conducted into potential uses of Chaetoceros in biotechnology.

May 14, 2024

Phytoplankton samples were collected on May 14, 2024 at Bullock Reach and analyzed in the laboratory shortly after collection. It was a beautiful day on Narragansett Bay with partly cloudy conditi​​ons and a slight breeze. Sonde data revealed the surface water temperature was 14.67°C, salinity was 21.36 psu, and chlorophyll a was 8.77 ug/L. Secchi disk water clarity was 3.4 m.​ The qualitative tow net sample had a long filtration time, and the filtrate was​​​ dark brown and ​cloudy. 

The analysis of the quantitative whole water sample revealed a total of 8,741,000 cells per Liter. The most predominant phytoplankton genus was Skeletonema spp. at 4,912,000 cells/L. Other  representative genera include Thalassiosira spp., Leptocylindrus  spp., and Chaetoceros spp. This week’s featured image (200x phase contrast) shows the diversity of the​​ phytoplankton sample, containing many different genera. Phytoplankton are primary producers and contain chlorophyll to capture sunlight to produce energy.

Week of July 22 – July 28, 2024

​Phillipsdale Landing

Sondes were swapped this week on the morning of July 23rd.  Overall, water quality at Phillipsdale Landing was good to fair this week. Weather conditions included sporadic rain events, with 0.46 inches of precipitation recorded at T.F. Green. The Blackstone River flow fluctuate through the week in response to rain, while remaining below the 19-year daily median. Surface salinity averaged 20.9 ppt and ranged from 0.0 ppt to 25.4 ppt. At the bottom, salinity averaged 23.3 ppt and ranged from 14.7 ppt to 27.4 ppt. Temperatures continued to increase this week, averaging 24.6°C at the surface and ranging 23.6°C – 26.2°C. At the bottom, temperatures averaged 23.9°C and ranged 22.3°C – 25.6°C.

Dissolved oxygen (DO) at Phillipsdale Landing dropped below the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO average 5.7 mg/L and ranged from 1.9 mg/L to 14.1 mg/L. Bottom DO concentrations averaged 3.4 mg/L and ranged from 0.7 mg/L to 9.5 mg/L. The longest period of hypoxic conditions (15 hours, 15 minutes) occurred at the bottom depth between the afternoons of July 24th and July 25th. During this period, bottom DO averaged around 2.28 mg/L. Chlorophyll readings decreased from last week, averaging 23.8 µg/L at the surface and 18.3 µg/L at the bottom. Maximum chlorophyll at the surface reached 132.3 µg/L on the afternoon of July 25th. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location. 

Bullock Reach

Overall, water quality was good to fair at Bullock Reach this week. Salinity averaged 25.6 ppt, 27.4 ppt, and 29.2 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 23.4 – 27.5 ppt, mid salinity ranged 13.3 – 29.3 ppt, and bottom salinity ranged 27.1 – 30.1 ppt. Surface temperature averaged 24.2°C and ranged from 22.9°C to 26.1°C. Mid temperatures averaged 23.4°C and ranged from 21.2°C to 25.8°C. Bottom temperatures averaged 21.4°C and ranged from 19.9°C to 24.1°C.

DO at Bullock Reach remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week at the surface. Middle and Bottom DO dropped below the hypoxia threshold frequently throughout the week. Surface DO averaged 6.5 mg/L and ranged 3.7 – 10.3 mg/L. In the mid waters, DO averaged 4.6 mg/L and ranged 2.7 – 8.9 mg/L. At the bottom, DO averaged 3.1 mg/L and ranged 1.9 – 4.9 mg/L.  

The longest period of hypoxic conditions (1 day, 2 hours, and 45 minutes) occurred at the bottom depth between the morning of July 22nd and the afternoon of July 23rd.  During this period, bottom DO averaged around 2.44 mg/L. Chlorophyll readings ranged from low to elevated, with evidence of moderate phytoplankton blooms occurring throughout the week. Readings averaged 12.7 µg/L at the surface, 9.5 µg/L at mid-depth, and 5.6 µg/L at the bottom.  The maximum surface chlorophyll was 42.4 µg/L on the morning of July 28th. ​

Week of July 15 – July 21, 2024

​Phillipsdale Landing

Overall, water quality at Phillipsdale Landing was fair this week. Weather conditions were dry, with only 0.79 inches recorded at T.F. Green. The Blackstone River flow continued an overall decreasing trend through the week. Surface salinity averaged 10.6 ppt and ranged from 2.6 ppt to 22.3 ppt. At the bottom, salinity averaged 20.3 ppt and ranged from 4.9 ppt to 27.3 ppt. Temperatures continued to increase this week, averaging 27.0°C at the surface and ranging 23.5°C – 30.6°C. At the bottom, temperatures averaged 24.5°C and ranged 21.3°C – 29.0°C. 

Dissolved oxygen (DO) at Phillipsdale Landing dropped below the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO average 9.1 mg/L and ranged from 0.7 mg/L to 17.3 mg/L. Bottom DO concentrations averaged 2.6 mg/L and ranged from 0.6 mg/L to 9.7 mg/L. The longest period of hypoxic conditions (22 hours) occurred from mid-day on July 18th to the morning of July 19th. During this period, bottom DO averaged around 1.54 mg/L. Chlorophyll readings decreased from last week, averaging 50.9 µg/L at the surface and 28.1 µg/L at the bottom. Maximum chlorophyll at the surface reached 329.3 µg/L on the morning of July 17th. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location. 

Bullock Reach

Sondes were swapped this week on the morning of July 16th. Overall, water quality was good to fair at Bullock Reach this week. Salinity averaged 23.3 ppt, 26.1 ppt, and 29.5 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 20.0 – 26.4 ppt, mid salinity ranged 23.4 – 29.3 ppt, and bottom salinity ranged 27.87 – 30.7 ppt. Surface temperature averaged 26.6°C and ranged from 24.3°C to 28.9°C. Mid temperatures averaged 25.2°C and ranged from 21.4°C to 27.8°C. Bottom temperatures averaged 21.0°C and ranged from 19.1°C to 22.7°C.

DO at Bullock Reach remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week at the surface. Middle and Bottom DO dropped below the hypoxia threshold frequently throughout the week. Surface DO averaged 7.2 mg/L and ranged 4.4 – 9.3 mg/L. In the mid waters, DO averaged 4.8 mg/L and ranged 1.6 – 7.8 mg/L. At the bottom, DO averaged 2.2 mg/L and ranged 1.3 – 3.6 mg/L.  The longest period of hypoxic conditions (2 days and 7 hours) occurred at the bottom depth between the night of July 16th and the morning of July 19th.  During this period, bottom DO averaged around 1.85 mg/L. Chlorophyll readings ranged from low to elevated, with evidence of moderate phytoplankton blooms occurring throughout the week. Readings averaged 11.2 µg/L at the surface, 13.4 µg/L at mid-depth, and 4.1 µg/L at the bottom. The maximum surface chlorophyll was 28.5 µg/L on the morning of July 15th. 

Week of July 8 – July 14, 2024

​Phillipsdale Landing

Sondes were swapped this week on the morning of July 9th. Overall, water quality at Phillipsdale Landing was good this week. Weather conditions were dry, with only 0.48 inches on July 13th, recorded at T.F. Green. The Blackstone River flow declined this week, dropping below the 19-year daily median mid-week.  Surface salinity averaged 9.0 ppt and ranged from 2.6 ppt to 18.0 ppt. At the bottom, salinity averaged 17.7 ppt and ranged from 5.1 ppt to 25.1 ppt. Temperatures continued to increase this week, averaging 26.8°C at the surface and ranging 24.8°C – 30.6°C. At the bottom, temperatures averaged 24.8°C and ranged 22.0°C – 28.7°C. 

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) at the surface throughout the week, while DO at the bottom waters remained below the hypoxic threshold for most of the week. Surface DO average 10.1 mg/L and ranged from 4.5 mg/L to 19.1 mg/L. Bottom DO concentrations averaged 4.1 mg/L and ranged from 0.8 mg/L to 13.3 mg/L. The longest period of hypoxic conditions (10 hours, 45 minutes) occurred at the bottom depth from the morning to afternoon of July 14th. During this period, bottom DO averaged around 1.68 mg/L. Chlorophyll readings rose from last week, averaging 85.8 µg/L at the surface and 46.4 µg/L at the bottom. Maximum chlorophyll at the surface reached 261.8 µg/L on the morning of July 9th. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location. 

Bullock Reach

Overall, water quality was good at Bullock Reach this week. Salinity averaged 23.4 ppt, 25.9 ppt, and 28.8 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 19.9 – 26.2 ppt, mid salinity ranged 23.2 -28.2 ppt, and bottom salinity ranged 26.3 – 30.4 ppt. Surface temperature averaged 25.7°C and ranged from 23.6°C to 27.9°C. Mid temperatures averaged 24.7°C and ranged from 20.9°C to 26.2°C. Bottom temperatures averaged 21.6°C and ranged from 19.3°C to 25.3°C.

DO at Bullock Reach remained above the hypoxia threshold (i.e., DO >2.9 mg/L) at the surface and middle depths throughout the week. Bottom DO dropped below the threshold, with the longest hypoxic period (11 hours and 15 minutes) occurring between the night of July 13th and the morning of July 14th. 

During this period, the bottom DO averaged around 2.52 mg/L. Surface DO averaged 7.3 mg/L and ranged 4.5 – 12.0 mg/L. In the mid waters, DO averaged 5.9 mg/L and ranged 3.2 – 8.2 mg/L. At the bottom, DO averaged 3.7 mg/L and ranged 2.1 – 6.5 mg/L.  Chlorophyll readings ranged from low to elevated, with evidence of moderate phytoplankton blooms occurring throughout the week. Readings averaged 18.4 µg/L at the surface, 15.0 µg/L at mid-depth, and 4.1 µg/L at the bottom.  The maximum surface chlorophyll was 52.8 µg/L on the afternoon of July 8th.  

Week of July 1 – July 7, 2024

Phillipsdale Landing

Overall, water quality at Phillipsdale Landing was good this week. Weather conditions included sporadic rain events, with 0.83 inches of precipitation recorded at T.F. Green. The Blackstone River flow fluctuate through the week in response to sporadic rain events. salinity averaged 13.9 ppt and ranged from 2.9 ppt to 22.8 ppt. At the bottom, salinity averaged 21.1 ppt and ranged from 7.2 ppt to 28.2 ppt. Temperatures continued to increase this week, averaging 25.6°C at the surface and ranging 23.3°C – 28.5°C. At the bottom, temperatures averaged 22.3°C and ranged 19.7°C – 24.5°C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) at the surface throughout the week. DO sporadically dropped below the threshold in the bottom waters. Surface DO average 8.7 mg/L and ranged from 3.4 mg/L to 18.4 mg/L. Bottom DO concentrations averaged 5.2 mg/L and ranged from 2.8 mg/L to 11.1 mg/L. The longest period of hypoxic conditions (1 hour) occurred in the afternoon of July 2nd. During this period, bottom DO averaged around 2.84 mg/L. Chlorophyll readings rose from last week, averaging 63.5 µg/L at the surface and 33.4 µg/L at the bottom. Maximum chlorophyll at the surface reached 125.4 µg/L on the night of July 4th. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location. 

Bullock Reach

Sondes were swapped this week on the morning of July 2nd. Overall, water quality was good at Bullock Reach this week. Salinity averaged 24.5 ppt, 26.7 ppt, and 28.8 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 20.8 – 26.6 ppt, mid salinity ranged 22.8 – 30.3 ppt, and bottom salinity ranged 26.9 – 30.5 ppt. Surface temperature averaged 22.9°C and ranged from 21.2°C to 25.3°C. Mid temperatures averaged 22.0°C and ranged from 18.7°C to 23.8°C. Bottom temperatures averaged 20.0°C and ranged from 17.8°C to 23.0°C.

DO at Bullock Reach remained above the hypoxia threshold (i.e., DO >2.9 mg/L) at all depths throughout the week.  Surface DO averaged 7.5 mg/L and ranged 4.8 – 12.5 mg/L. In the mid waters, DO averaged 6.3 mg/L and ranged 4.1 – 8.4 mg/L. At the bottom, DO averaged 4.7 mg/L and ranged 3.3 – 6.9 mg/L.  Chlorophyll readings ranged from low to elevated, with evidence of moderate phytoplankton blooms occurring throughout the week. Readings averaged 16.3 µg/L at the surface, 13.0 µg/L at mid-depth, and 4.9 µg/L at the bottom.  The maximum surface chlorophyll was 48.3 µg/L on the afternoon of July 2nd. 

Week of June 24 – June 30, 2024

​Phillipsdale Landing

Sondes were swapped this week on the morning of June 25th. Overall, water quality at Phillipsdale Landing was fair this week. Weather conditions included sporadic rain events, with 2.17 inches of precipitation recorded at T.F. Green. The Blackstone River flow fluctuate through the week in response to rain, while still remaining above the 19-year daily median. Surface salinity averaged 9.1 ppt and ranged from 2.6 ppt to 20.3 ppt. At the bottom, salinity averaged 18.6 ppt and ranged from 5.4 ppt to 28.1 ppt. Temperatures continued to increase this week, averaging 25.1°C at the surface and ranging 22.0°C – 27.8°C. At the bottom, temperatures averaged 22.1°C and ranged 19.6°C – 24.7°C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) at the surface throughout the week. DO sporadically dropped below the threshold in the bottom waters. Surface DO average 7.44 mg/L and ranged from 3.99 mg/L to 11.35 mg/L. Bottom DO concentrations averaged 4.5 mg/L and ranged from 2.2 mg/L to 10.3 mg/L. Chlorophyll readings dropped slightly from last week, averaging 28.64 µg/L at the surface and 19.9 µg/L at the bottom. Maximum chlorophyll at the surface reached 81.2 µg/L on the morning of June 30th. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location. 

Bullock Reach

Overall, water quality was good at Bullock Reach this week. Salinity averaged 24.7 ppt, 28.2 ppt, and 27.3 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 20.9 – 27.2 ppt, mid salinity ranged 25.1 – 29.8 ppt, and bottom salinity ranged 23.1 – 30.3 ppt. Surface temperature averaged 22.5°C and ranged from 21.1°C to 25.1°C. Mid temperatures averaged 19.8°C and ranged from 17.8°C to 22.2°C. Bottom temperatures averaged 21.5°C and ranged from 18.5°C to 23.3°C.

DO at Bullock Reach remained above the hypoxia threshold (i.e., DO >2.9 mg/L) at all depths throughout the week.  Surface DO averaged 7.5 mg/L and ranged 5.3 – 10.9 mg/L. In the mid waters, DO averaged 4.8 mg/L and ranged 3.1 – 6.8 mg/L. At the bottom, DO averaged 6.2 mg/L and ranged 4.3– 8.8 mg/L.  Chlorophyll readings ranged from low to elevated, with evidence of moderate phytoplankton blooms occurring throughout the month. Readings averaged 17.1 µg/L at the surface, 8.2 µg/L at mid-depth, and 18.3 µg/L at the bottom. The maximum surface chlorophyll was 51.1 µg/L on the afternoon of June 28th.

Week of June 17 – June 23, 2024

​Phillipsdale Landing

Overall, water quality at Phillipsdale Landing was fair this week. Weather conditions included sporadic rain events, with 2.22 inches of precipitation recorded at T.F. Green. The Blackstone River flow fluctuate through the week in response to rain, while still remaining above the 19-year daily median. Surface salinity averaged 9.4 ppt and ranged from 2.5 ppt to 19.8 ppt. At the bottom, salinity averaged 18.9 ppt and ranged from 5.9 ppt to 26.0 ppt. Temperatures continued to increase this week, averaging 23.9°C at the surface and ranging 20.6°C – 28.3°C. At the bottom, temperatures averaged 21.4°C and ranged 18.3°C – 25.5°C.

Dissolved oxygen (DO) at Phillipsdale Landing has remained high at the surface, with only a few dropped readings below the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO was lower than the previous week, averaging 8.3 mg/L and ranging 2.65 mg/L to 14.1 mg/L. Bottom DO concentrations dropped below the hypoxia level (i.e., DO <2.9 mg/L) briefly this week, averaging 4.2 mg/L and ranged from 2.0 mg/L to 10.0 mg/L. Chlorophyll readings have risen from last week, averaging 35.54 µg/L at the surface and 27.7 µg/L at the bottom. Maximum chlorophyll at the surface reached 98.2 µg/L on the night of June 21st. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location. 

Bullock Reach

Sondes were swapped this week on the morning of June 18th. Overall, water quality was good at Bullock Reach this week. Salinity averaged 23.9 ppt, 28.0 ppt, and 24.0 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 19.3 – 27.0 ppt, mid salinity ranged 25.1 – 30.0 ppt, and bottom salinity ranged 0.0 – 29.9 ppt. Surface temperature averaged 23.3°C and ranged from 19.8°C to 26.1°C. Mid temperatures averaged 18.8°C and ranged from 16.4°C to 21.9°C. Bottom temperatures averaged 21.5°C and ranged from 15.7°C to 25.0°C.

DO at Bullock Reach remained above the hypoxia threshold (i.e., DO >2.9 mg/L) at all depths throughout the week.  Surface DO averaged 8.1 mg/L and ranged 5.7 – 11.6 mg/L. In the mid waters, DO averaged 5.0 mg/L and ranged 3.4 – 9.0 mg/L. At the bottom, DO averaged 6.6 mg/L and ranged 2.9– 9.4 mg/L.  Chlorophyll readings ranged from low to elevated, with evidence of moderate phytoplankton blooms occurring throughout the month. Readings averaged 15.8 µg/L at the surface, 8.4 µg/L at mid-depth, and 11.2 µg/L at the bottom.  The maximum surface chlorophyll was 47.9 µg/L on the morning of June 23rd. 

Week of June 10 – June 16, 2024

​Phillipsdale Landing

Sondes were swapped this week on the morning of June 11th. Overall, water quality at Phillipsdale Landing was good this week. Weather conditions were dry, with only 0.06 inches on June 14th, recorded at T.F. Green. The Blackstone River flow declined this week, dropping below the 19-year daily median mid-week. Surface salinity averaged 8.5 ppt and ranged from 3.2 ppt to 18.6 ppt. At the bottom, salinity averaged 20.3 ppt and ranged from 5.3 ppt to 26.7 ppt. Temperatures continued to increase this week, averaging 21.8°C at the surface and ranging 19.1°C – 24.5°C. At the bottom, temperatures averaged 19.0°C and ranged 16.2°C – 23.6°C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO average 10.7 mg/L and ranged from 5.36 mg/L to 20.3 mg/L. Bottom DO concentrations averaged 6.1 mg/L and ranged from 3.8 mg/L to 13.7 mg/L. Chlorophyll readings have risen from last week, averaging 26.64 µg/L at the surface and 19.6 µg/L at the bottom. Maximum chlorophyll at the surface reached 132.6 µg/L on the morning of June 16th. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location. 

Bullock Reach

Overall, water quality was good at Bullock Reach this week. Salinity averaged 23.5 ppt, 26.3 ppt, and 28.5 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 19.8 – 25.4 ppt, mid salinity ranged 22.2 – 28.5 ppt, and bottom salinity ranged 18.0 – 30.2 ppt. Surface temperature averaged 20.4°C and ranged from 18.3°C to 22.5°C. Mid temperatures averaged 19.2°C and ranged from 16.5°C to 21.8°C. Bottom temperatures averaged 16.5°C and ranged from 14.8°C to 20.3°C.

DO at Bullock Reach remained above the hypoxia threshold (i.e., DO >2.9 mg/L) at all depths throughout the week.  Surface DO averaged 9.2 mg/L and ranged 5.1 – 13.8 mg/L. In the mid waters, DO averaged 7.1 mg/L and ranged 4.9 – 8.9 mg/L. At the bottom, DO averaged 5.1 mg/L and ranged 3.6 – 6.6 mg/L.  Chlorophyll readings ranged from low to elevated, with evidence of moderate phytoplankton blooms occurring throughout the month. Readings averaged 10.4 µg/L at the surface, 8.5 µg/L at mid-depth, and 3.3 µg/L at the bottom. The maximum surface chlorophyll was 41.5 µg/L on the morning of June 11th. 

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